// Tencent is pleased to support the open source community by making RapidJSON available.
//
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// http://opensource.org/licenses/MIT
//
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.

#ifndef RAPIDJSON_ENCODINGS_H_
#define RAPIDJSON_ENCODINGS_H_

#include "rapidjson.h"

#ifdef _MSC_VER
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(4244) // conversion from 'type1' to 'type2', possible loss of data
RAPIDJSON_DIAG_OFF(4702) // unreachable code
#elif defined(__GNUC__)
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(effc++)
RAPIDJSON_DIAG_OFF(overflow)
#endif

RAPIDJSON_NAMESPACE_BEGIN

///////////////////////////////////////////////////////////////////////////////
// Encoding

/*! \class rapidjson::Encoding
    \brief Concept for encoding of Unicode characters.

\code
concept Encoding {
    typename Ch;    //! Type of character. A "character" is actually a code unit in unicode's definition.

    enum { supportUnicode = 1 }; // or 0 if not supporting unicode

    //! \brief Encode a Unicode codepoint to an output stream.
    //! \param os Output stream.
    //! \param codepoint An unicode codepoint, ranging from 0x0 to 0x10FFFF inclusively.
    template<typename OutputStream>
    static void Encode(OutputStream& os, unsigned codepoint);

    //! \brief Decode a Unicode codepoint from an input stream.
    //! \param is Input stream.
    //! \param codepoint Output of the unicode codepoint.
    //! \return true if a valid codepoint can be decoded from the stream.
    template <typename InputStream>
    static bool Decode(InputStream& is, unsigned* codepoint);

    //! \brief Validate one Unicode codepoint from an encoded stream.
    //! \param is Input stream to obtain codepoint.
    //! \param os Output for copying one codepoint.
    //! \return true if it is valid.
    //! \note This function just validating and copying the codepoint without actually decode it.
    template <typename InputStream, typename OutputStream>
    static bool Validate(InputStream& is, OutputStream& os);

    // The following functions are deal with byte streams.

    //! Take a character from input byte stream, skip BOM if exist.
    template <typename InputByteStream>
    static CharType TakeBOM(InputByteStream& is);

    //! Take a character from input byte stream.
    template <typename InputByteStream>
    static Ch Take(InputByteStream& is);

    //! Put BOM to output byte stream.
    template <typename OutputByteStream>
    static void PutBOM(OutputByteStream& os);

    //! Put a character to output byte stream.
    template <typename OutputByteStream>
    static void Put(OutputByteStream& os, Ch c);
};
\endcode
*/

///////////////////////////////////////////////////////////////////////////////
// UTF8

//! UTF-8 encoding.
/*! http://en.wikipedia.org/wiki/UTF-8
    http://tools.ietf.org/html/rfc3629
    \tparam CharType Code unit for storing 8-bit UTF-8 data. Default is char.
    \note implements Encoding concept
*/
template <typename CharType = char>
struct UTF8 {
	typedef CharType Ch;

	enum { supportUnicode = 1 };

	template <typename OutputStream>
	static void Encode(OutputStream& os, unsigned codepoint) {
		if (codepoint <= 0x7F)
			os.Put(static_cast<Ch>(codepoint & 0xFF));
		else if (codepoint <= 0x7FF) {
			os.Put(static_cast<Ch>(0xC0 | ((codepoint >> 6) & 0xFF)));
			os.Put(static_cast<Ch>(0x80 | ((codepoint & 0x3F))));
		} else if (codepoint <= 0xFFFF) {
			os.Put(static_cast<Ch>(0xE0 | ((codepoint >> 12) & 0xFF)));
			os.Put(static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
			os.Put(static_cast<Ch>(0x80 | (codepoint & 0x3F)));
		} else {
			RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
			os.Put(static_cast<Ch>(0xF0 | ((codepoint >> 18) & 0xFF)));
			os.Put(static_cast<Ch>(0x80 | ((codepoint >> 12) & 0x3F)));
			os.Put(static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
			os.Put(static_cast<Ch>(0x80 | (codepoint & 0x3F)));
		}
	}

	template <typename OutputStream>
	static void EncodeUnsafe(OutputStream& os, unsigned codepoint) {
		if (codepoint <= 0x7F)
			PutUnsafe(os, static_cast<Ch>(codepoint & 0xFF));
		else if (codepoint <= 0x7FF) {
			PutUnsafe(os, static_cast<Ch>(0xC0 | ((codepoint >> 6) & 0xFF)));
			PutUnsafe(os, static_cast<Ch>(0x80 | ((codepoint & 0x3F))));
		} else if (codepoint <= 0xFFFF) {
			PutUnsafe(os, static_cast<Ch>(0xE0 | ((codepoint >> 12) & 0xFF)));
			PutUnsafe(os, static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
			PutUnsafe(os, static_cast<Ch>(0x80 | (codepoint & 0x3F)));
		} else {
			RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
			PutUnsafe(os, static_cast<Ch>(0xF0 | ((codepoint >> 18) & 0xFF)));
			PutUnsafe(os, static_cast<Ch>(0x80 | ((codepoint >> 12) & 0x3F)));
			PutUnsafe(os, static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
			PutUnsafe(os, static_cast<Ch>(0x80 | (codepoint & 0x3F)));
		}
	}

	template <typename InputStream>
	static bool Decode(InputStream& is, unsigned* codepoint) {
#define COPY()                                                                                                         \
	c = is.Take();                                                                                                     \
	*codepoint = (*codepoint << 6) | (static_cast<unsigned char>(c) & 0x3Fu)
#define TRANS(mask) result &= ((GetRange(static_cast<unsigned char>(c)) & mask) != 0)
#define TAIL()                                                                                                         \
	COPY();                                                                                                            \
	TRANS(0x70)
		typename InputStream::Ch c = is.Take();
		if (!(c & 0x80)) {
			*codepoint = static_cast<unsigned char>(c);
			return true;
		}

		unsigned char type = GetRange(static_cast<unsigned char>(c));
		if (type >= 32) {
			*codepoint = 0;
		} else {
			*codepoint = (0xFF >> type) & static_cast<unsigned char>(c);
		}
		bool result = true;
		switch (type) {
		case 2:
			TAIL();
			return result;
		case 3:
			TAIL();
			TAIL();
			return result;
		case 4:
			COPY();
			TRANS(0x50);
			TAIL();
			return result;
		case 5:
			COPY();
			TRANS(0x10);
			TAIL();
			TAIL();
			return result;
		case 6:
			TAIL();
			TAIL();
			TAIL();
			return result;
		case 10:
			COPY();
			TRANS(0x20);
			TAIL();
			return result;
		case 11:
			COPY();
			TRANS(0x60);
			TAIL();
			TAIL();
			return result;
		default:
			return false;
		}
#undef COPY
#undef TRANS
#undef TAIL
	}

	template <typename InputStream, typename OutputStream>
	static bool Validate(InputStream& is, OutputStream& os) {
#define COPY() os.Put(c = is.Take())
#define TRANS(mask) result &= ((GetRange(static_cast<unsigned char>(c)) & mask) != 0)
#define TAIL()                                                                                                         \
	COPY();                                                                                                            \
	TRANS(0x70)
		Ch c;
		COPY();
		if (!(c & 0x80))
			return true;

		bool result = true;
		switch (GetRange(static_cast<unsigned char>(c))) {
		case 2:
			TAIL();
			return result;
		case 3:
			TAIL();
			TAIL();
			return result;
		case 4:
			COPY();
			TRANS(0x50);
			TAIL();
			return result;
		case 5:
			COPY();
			TRANS(0x10);
			TAIL();
			TAIL();
			return result;
		case 6:
			TAIL();
			TAIL();
			TAIL();
			return result;
		case 10:
			COPY();
			TRANS(0x20);
			TAIL();
			return result;
		case 11:
			COPY();
			TRANS(0x60);
			TAIL();
			TAIL();
			return result;
		default:
			return false;
		}
#undef COPY
#undef TRANS
#undef TAIL
	}

	static unsigned char GetRange(unsigned char c) {
		// Referring to DFA of http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
		// With new mapping 1 -> 0x10, 7 -> 0x20, 9 -> 0x40, such that AND operation can test multiple types.
		static const unsigned char type[] = {
			0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
			0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
			0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
			0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
			0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
			0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
			0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
			0,    0,    0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,
			0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x20, 0x20,
			0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
			0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 8,    8,    2,    2,    2,    2,
			2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,
			2,    2,    2,    2,    2,    2,    2,    2,    10,   3,    3,    3,    3,    3,    3,    3,    3,    3,
			3,    3,    3,    4,    3,    3,    11,   6,    6,    6,    5,    8,    8,    8,    8,    8,    8,    8,
			8,    8,    8,    8,
		};
		return type[c];
	}

	template <typename InputByteStream>
	static CharType TakeBOM(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		typename InputByteStream::Ch c = Take(is);
		if (static_cast<unsigned char>(c) != 0xEFu)
			return c;
		c = is.Take();
		if (static_cast<unsigned char>(c) != 0xBBu)
			return c;
		c = is.Take();
		if (static_cast<unsigned char>(c) != 0xBFu)
			return c;
		c = is.Take();
		return c;
	}

	template <typename InputByteStream>
	static Ch Take(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		return static_cast<Ch>(is.Take());
	}

	template <typename OutputByteStream>
	static void PutBOM(OutputByteStream& os) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>(0xEFu));
		os.Put(static_cast<typename OutputByteStream::Ch>(0xBBu));
		os.Put(static_cast<typename OutputByteStream::Ch>(0xBFu));
	}

	template <typename OutputByteStream>
	static void Put(OutputByteStream& os, Ch c) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>(c));
	}
};

///////////////////////////////////////////////////////////////////////////////
// UTF16

//! UTF-16 encoding.
/*! http://en.wikipedia.org/wiki/UTF-16
    http://tools.ietf.org/html/rfc2781
    \tparam CharType Type for storing 16-bit UTF-16 data. Default is wchar_t. C++11 may use char16_t instead.
    \note implements Encoding concept

    \note For in-memory access, no need to concern endianness. The code units and code points are represented by CPU's
   endianness. For streaming, use UTF16LE and UTF16BE, which handle endianness.
*/
template <typename CharType = wchar_t>
struct UTF16 {
	typedef CharType Ch;
	RAPIDJSON_STATIC_ASSERT(sizeof(Ch) >= 2);

	enum { supportUnicode = 1 };

	template <typename OutputStream>
	static void Encode(OutputStream& os, unsigned codepoint) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 2);
		if (codepoint <= 0xFFFF) {
			RAPIDJSON_ASSERT(codepoint < 0xD800 || codepoint > 0xDFFF); // Code point itself cannot be surrogate pair
			os.Put(static_cast<typename OutputStream::Ch>(codepoint));
		} else {
			RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
			unsigned v = codepoint - 0x10000;
			os.Put(static_cast<typename OutputStream::Ch>((v >> 10) | 0xD800));
			os.Put((v & 0x3FF) | 0xDC00);
		}
	}

	template <typename OutputStream>
	static void EncodeUnsafe(OutputStream& os, unsigned codepoint) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 2);
		if (codepoint <= 0xFFFF) {
			RAPIDJSON_ASSERT(codepoint < 0xD800 || codepoint > 0xDFFF); // Code point itself cannot be surrogate pair
			PutUnsafe(os, static_cast<typename OutputStream::Ch>(codepoint));
		} else {
			RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
			unsigned v = codepoint - 0x10000;
			PutUnsafe(os, static_cast<typename OutputStream::Ch>((v >> 10) | 0xD800));
			PutUnsafe(os, (v & 0x3FF) | 0xDC00);
		}
	}

	template <typename InputStream>
	static bool Decode(InputStream& is, unsigned* codepoint) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 2);
		typename InputStream::Ch c = is.Take();
		if (c < 0xD800 || c > 0xDFFF) {
			*codepoint = static_cast<unsigned>(c);
			return true;
		} else if (c <= 0xDBFF) {
			*codepoint = (static_cast<unsigned>(c) & 0x3FF) << 10;
			c = is.Take();
			*codepoint |= (static_cast<unsigned>(c) & 0x3FF);
			*codepoint += 0x10000;
			return c >= 0xDC00 && c <= 0xDFFF;
		}
		return false;
	}

	template <typename InputStream, typename OutputStream>
	static bool Validate(InputStream& is, OutputStream& os) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 2);
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 2);
		typename InputStream::Ch c;
		os.Put(static_cast<typename OutputStream::Ch>(c = is.Take()));
		if (c < 0xD800 || c > 0xDFFF)
			return true;
		else if (c <= 0xDBFF) {
			os.Put(c = is.Take());
			return c >= 0xDC00 && c <= 0xDFFF;
		}
		return false;
	}
};

//! UTF-16 little endian encoding.
template <typename CharType = wchar_t>
struct UTF16LE : UTF16<CharType> {
	template <typename InputByteStream>
	static CharType TakeBOM(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		CharType c = Take(is);
		return static_cast<uint16_t>(c) == 0xFEFFu ? Take(is) : c;
	}

	template <typename InputByteStream>
	static CharType Take(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		unsigned c = static_cast<uint8_t>(is.Take());
		c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 8;
		return static_cast<CharType>(c);
	}

	template <typename OutputByteStream>
	static void PutBOM(OutputByteStream& os) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>(0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>(0xFEu));
	}

	template <typename OutputByteStream>
	static void Put(OutputByteStream& os, CharType c) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>(static_cast<unsigned>(c) & 0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>((static_cast<unsigned>(c) >> 8) & 0xFFu));
	}
};

//! UTF-16 big endian encoding.
template <typename CharType = wchar_t>
struct UTF16BE : UTF16<CharType> {
	template <typename InputByteStream>
	static CharType TakeBOM(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		CharType c = Take(is);
		return static_cast<uint16_t>(c) == 0xFEFFu ? Take(is) : c;
	}

	template <typename InputByteStream>
	static CharType Take(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		unsigned c = static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 8;
		c |= static_cast<uint8_t>(is.Take());
		return static_cast<CharType>(c);
	}

	template <typename OutputByteStream>
	static void PutBOM(OutputByteStream& os) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>(0xFEu));
		os.Put(static_cast<typename OutputByteStream::Ch>(0xFFu));
	}

	template <typename OutputByteStream>
	static void Put(OutputByteStream& os, CharType c) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>((static_cast<unsigned>(c) >> 8) & 0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>(static_cast<unsigned>(c) & 0xFFu));
	}
};

///////////////////////////////////////////////////////////////////////////////
// UTF32

//! UTF-32 encoding.
/*! http://en.wikipedia.org/wiki/UTF-32
    \tparam CharType Type for storing 32-bit UTF-32 data. Default is unsigned. C++11 may use char32_t instead.
    \note implements Encoding concept

    \note For in-memory access, no need to concern endianness. The code units and code points are represented by CPU's
   endianness. For streaming, use UTF32LE and UTF32BE, which handle endianness.
*/
template <typename CharType = unsigned>
struct UTF32 {
	typedef CharType Ch;
	RAPIDJSON_STATIC_ASSERT(sizeof(Ch) >= 4);

	enum { supportUnicode = 1 };

	template <typename OutputStream>
	static void Encode(OutputStream& os, unsigned codepoint) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 4);
		RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
		os.Put(codepoint);
	}

	template <typename OutputStream>
	static void EncodeUnsafe(OutputStream& os, unsigned codepoint) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 4);
		RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
		PutUnsafe(os, codepoint);
	}

	template <typename InputStream>
	static bool Decode(InputStream& is, unsigned* codepoint) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 4);
		Ch c = is.Take();
		*codepoint = c;
		return c <= 0x10FFFF;
	}

	template <typename InputStream, typename OutputStream>
	static bool Validate(InputStream& is, OutputStream& os) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 4);
		Ch c;
		os.Put(c = is.Take());
		return c <= 0x10FFFF;
	}
};

//! UTF-32 little endian enocoding.
template <typename CharType = unsigned>
struct UTF32LE : UTF32<CharType> {
	template <typename InputByteStream>
	static CharType TakeBOM(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		CharType c = Take(is);
		return static_cast<uint32_t>(c) == 0x0000FEFFu ? Take(is) : c;
	}

	template <typename InputByteStream>
	static CharType Take(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		unsigned c = static_cast<uint8_t>(is.Take());
		c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 8;
		c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 16;
		c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 24;
		return static_cast<CharType>(c);
	}

	template <typename OutputByteStream>
	static void PutBOM(OutputByteStream& os) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>(0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>(0xFEu));
		os.Put(static_cast<typename OutputByteStream::Ch>(0x00u));
		os.Put(static_cast<typename OutputByteStream::Ch>(0x00u));
	}

	template <typename OutputByteStream>
	static void Put(OutputByteStream& os, CharType c) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>(c & 0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>((c >> 8) & 0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>((c >> 16) & 0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>((c >> 24) & 0xFFu));
	}
};

//! UTF-32 big endian encoding.
template <typename CharType = unsigned>
struct UTF32BE : UTF32<CharType> {
	template <typename InputByteStream>
	static CharType TakeBOM(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		CharType c = Take(is);
		return static_cast<uint32_t>(c) == 0x0000FEFFu ? Take(is) : c;
	}

	template <typename InputByteStream>
	static CharType Take(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		unsigned c = static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 24;
		c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 16;
		c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 8;
		c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take()));
		return static_cast<CharType>(c);
	}

	template <typename OutputByteStream>
	static void PutBOM(OutputByteStream& os) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>(0x00u));
		os.Put(static_cast<typename OutputByteStream::Ch>(0x00u));
		os.Put(static_cast<typename OutputByteStream::Ch>(0xFEu));
		os.Put(static_cast<typename OutputByteStream::Ch>(0xFFu));
	}

	template <typename OutputByteStream>
	static void Put(OutputByteStream& os, CharType c) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>((c >> 24) & 0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>((c >> 16) & 0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>((c >> 8) & 0xFFu));
		os.Put(static_cast<typename OutputByteStream::Ch>(c & 0xFFu));
	}
};

///////////////////////////////////////////////////////////////////////////////
// ASCII

//! ASCII encoding.
/*! http://en.wikipedia.org/wiki/ASCII
    \tparam CharType Code unit for storing 7-bit ASCII data. Default is char.
    \note implements Encoding concept
*/
template <typename CharType = char>
struct ASCII {
	typedef CharType Ch;

	enum { supportUnicode = 0 };

	template <typename OutputStream>
	static void Encode(OutputStream& os, unsigned codepoint) {
		RAPIDJSON_ASSERT(codepoint <= 0x7F);
		os.Put(static_cast<Ch>(codepoint & 0xFF));
	}

	template <typename OutputStream>
	static void EncodeUnsafe(OutputStream& os, unsigned codepoint) {
		RAPIDJSON_ASSERT(codepoint <= 0x7F);
		PutUnsafe(os, static_cast<Ch>(codepoint & 0xFF));
	}

	template <typename InputStream>
	static bool Decode(InputStream& is, unsigned* codepoint) {
		uint8_t c = static_cast<uint8_t>(is.Take());
		*codepoint = c;
		return c <= 0X7F;
	}

	template <typename InputStream, typename OutputStream>
	static bool Validate(InputStream& is, OutputStream& os) {
		uint8_t c = static_cast<uint8_t>(is.Take());
		os.Put(static_cast<typename OutputStream::Ch>(c));
		return c <= 0x7F;
	}

	template <typename InputByteStream>
	static CharType TakeBOM(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		uint8_t c = static_cast<uint8_t>(Take(is));
		return static_cast<Ch>(c);
	}

	template <typename InputByteStream>
	static Ch Take(InputByteStream& is) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
		return static_cast<Ch>(is.Take());
	}

	template <typename OutputByteStream>
	static void PutBOM(OutputByteStream& os) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		(void)os;
	}

	template <typename OutputByteStream>
	static void Put(OutputByteStream& os, Ch c) {
		RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
		os.Put(static_cast<typename OutputByteStream::Ch>(c));
	}
};

///////////////////////////////////////////////////////////////////////////////
// AutoUTF

//! Runtime-specified UTF encoding type of a stream.
enum UTFType {
	kUTF8 = 0, //!< UTF-8.
	kUTF16LE = 1, //!< UTF-16 little endian.
	kUTF16BE = 2, //!< UTF-16 big endian.
	kUTF32LE = 3, //!< UTF-32 little endian.
	kUTF32BE = 4 //!< UTF-32 big endian.
};

//! Dynamically select encoding according to stream's runtime-specified UTF encoding type.
/*! \note This class can be used with AutoUTFInputtStream and AutoUTFOutputStream, which provides GetType().
 */
template <typename CharType>
struct AutoUTF {
	typedef CharType Ch;

	enum { supportUnicode = 1 };

#define RAPIDJSON_ENCODINGS_FUNC(x) UTF8<Ch>::x, UTF16LE<Ch>::x, UTF16BE<Ch>::x, UTF32LE<Ch>::x, UTF32BE<Ch>::x

	template <typename OutputStream>
	RAPIDJSON_FORCEINLINE static void Encode(OutputStream& os, unsigned codepoint) {
		typedef void (*EncodeFunc)(OutputStream&, unsigned);
		static const EncodeFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(Encode) };
		(*f[os.GetType()])(os, codepoint);
	}

	template <typename OutputStream>
	RAPIDJSON_FORCEINLINE static void EncodeUnsafe(OutputStream& os, unsigned codepoint) {
		typedef void (*EncodeFunc)(OutputStream&, unsigned);
		static const EncodeFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(EncodeUnsafe) };
		(*f[os.GetType()])(os, codepoint);
	}

	template <typename InputStream>
	RAPIDJSON_FORCEINLINE static bool Decode(InputStream& is, unsigned* codepoint) {
		typedef bool (*DecodeFunc)(InputStream&, unsigned*);
		static const DecodeFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(Decode) };
		return (*f[is.GetType()])(is, codepoint);
	}

	template <typename InputStream, typename OutputStream>
	RAPIDJSON_FORCEINLINE static bool Validate(InputStream& is, OutputStream& os) {
		typedef bool (*ValidateFunc)(InputStream&, OutputStream&);
		static const ValidateFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(Validate) };
		return (*f[is.GetType()])(is, os);
	}

#undef RAPIDJSON_ENCODINGS_FUNC
};

///////////////////////////////////////////////////////////////////////////////
// Transcoder

//! Encoding conversion.
template <typename SourceEncoding, typename TargetEncoding>
struct Transcoder {
	//! Take one Unicode codepoint from source encoding, convert it to target encoding and put it to the output stream.
	template <typename InputStream, typename OutputStream>
	RAPIDJSON_FORCEINLINE static bool Transcode(InputStream& is, OutputStream& os) {
		unsigned codepoint;
		if (!SourceEncoding::Decode(is, &codepoint))
			return false;
		TargetEncoding::Encode(os, codepoint);
		return true;
	}

	template <typename InputStream, typename OutputStream>
	RAPIDJSON_FORCEINLINE static bool TranscodeUnsafe(InputStream& is, OutputStream& os) {
		unsigned codepoint;
		if (!SourceEncoding::Decode(is, &codepoint))
			return false;
		TargetEncoding::EncodeUnsafe(os, codepoint);
		return true;
	}

	//! Validate one Unicode codepoint from an encoded stream.
	template <typename InputStream, typename OutputStream>
	RAPIDJSON_FORCEINLINE static bool Validate(InputStream& is, OutputStream& os) {
		return Transcode(is, os); // Since source/target encoding is different, must transcode.
	}
};

// Forward declaration.
template <typename Stream>
inline void PutUnsafe(Stream& stream, typename Stream::Ch c);

//! Specialization of Transcoder with same source and target encoding.
template <typename Encoding>
struct Transcoder<Encoding, Encoding> {
	template <typename InputStream, typename OutputStream>
	RAPIDJSON_FORCEINLINE static bool Transcode(InputStream& is, OutputStream& os) {
		os.Put(is.Take()); // Just copy one code unit. This semantic is different from primary template class.
		return true;
	}

	template <typename InputStream, typename OutputStream>
	RAPIDJSON_FORCEINLINE static bool TranscodeUnsafe(InputStream& is, OutputStream& os) {
		PutUnsafe(os, is.Take()); // Just copy one code unit. This semantic is different from primary template class.
		return true;
	}

	template <typename InputStream, typename OutputStream>
	RAPIDJSON_FORCEINLINE static bool Validate(InputStream& is, OutputStream& os) {
		return Encoding::Validate(is, os); // source/target encoding are the same
	}
};

RAPIDJSON_NAMESPACE_END

#if defined(__GNUC__) || defined(_MSC_VER)
RAPIDJSON_DIAG_POP
#endif

#endif // RAPIDJSON_ENCODINGS_H_
